Mechanical conditioning influences the metabolic response of cell-seeded constructs

Injuries and degenerative diseases to load-bearing soft tissues are extremely common in hospital clinics and involve all ages of the population. Tissue engineering provides a major focus for developments within this area due to the relative failure of graft and prosthetic-based strategies. On implantation, such systems will be subjected to normal physiological forces. It is important, therefore, to understand the effects of mechanical conditioning of cells within repair systems to predict their response and ultimate success in vivo. In the current study two well-characterised model systems, involving dermal fibroblasts seeded onto silicone membranes and chondrocytes seeded in agarose constructs, have been used to study the effects of mechanical loading on cellular activity. The data presented demonstrate that both the tensile conditioning of fibroblasts in monolayer and the compressive loading of chondrocytes in three-dimensional agarose constructs produced distinct responses. In particular, the nature of the strain field associated with the tensile system is important in determining the ultimate cell response. Equally within the compressive system the influence of dynamic frequency was shown to be important. The other critical factors in determining response to both types of conditioning are associated with the age of the cell and its original location within the tissue.